1. Assistant Professor, Dept. of Civil Engineering, Kyung Hee Univ., 1732 Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 446-701, Republic of Korea; formerly, Assistant Professor, Dept. of Civil Engineering, Univ. of Suwon, Wauan-gil 17, Bongdam-sup, Hwaseong-si, Gyeonggi-do 445-743, South Korea (corresponding author).
2. Professor, Dept. of Civil Engineering and Engineering Mechanics, Univ. of Arizona, Tucson, AZ 85721.